1. Field of the Invention
The present invention relates to a building wall construction such as a multiple window or window wall, and more particularly to such a building wall construction including a corner unit.
2. Description of the Prior Art
Some building wall constructions known as multiple windows and window walls include various corners such as angular salient and re-entrant corners of 90.degree. and 135.degree. or round salient and re-entrant corners. For constructing such corners, a mullion is first secured as by an anchor to a corner region of an external building wall, and then vertical frame members are attached to the mullion. Where there is any column at the corner region, it has been troublesome to interconnect the mullion and the vertical frame members and glazed wall portions adjacent to the mullion. It has also been a complex task to install an insulation around the mullion. Accordingly, assembling prior building wall corners at a construction site has been a tedious and time-consuming job.
Another problem with the known building corner constructions is that they should be securely connected to adjacent parts to withstand loads due to thermal expansion and contraction of the adjacent parts such as window frames. The corner arrangements cannot be factory-assembled as they fail to provide a sufficient mechanical strength to bear the imposed loads. The mullions in the prior corners make the latter large in size and unsighly in appearance. The difficulty in assembling the building wall corners is such that a desired degree of airtightness and thermal insulation frequently cannot be achieved, the angles of corners cannot be gained to a nicety, and the corner mullions cannot securely be connected to the adjacent members.